preparation

For lamb:

Combine all ingredients in large bowl; turn lamb to coat with oil. Let stand at room temperature 1 hour. DO AHEAD Can be made 1 day ahead. Cover; chill. Let stand at room temperature 1 hour before cooking.

For pesto:

Blend first 5 ingredients in processor to coarse puree, occasionally scraping down sides of processor. Mix in lemon juice. Season with salt and pepper. Transfer to bowl. DO AHEAD Can be made 1 day ahead. Cover; chill.

Heat large griddle or large skillet over high heat. Add lamb chops with rosemary-garlic mixture. Cook to desired doneness, about 4 minutes per side for medium-rare. Transfer to plates; top with pesto.